The present invention relates generally to the non-destructive inspection and evaluation of materials using x-rays. More particularly, the present invention relates to a method of and system for performing non-destructive inspection and evaluation of materials by the computer processing of images produced on/by an image conversion screen/device.
When non-destructively inspecting and/or evaluating materials using x-rays, difficulties have arisen in creating images of the materials being tested or evaluated with regard to the detail of the fine structure in such materials. This lack of fine structural detail is due to the interference structures of the transmission components of the imaging system, for example, the interference structures of the input luminescent fluoroscopic screen or the semi-conductor materials of the CCD camera which translates the fluoroscopic image.
One approach to dealing with similar problems in an x-ray diagnostic installation is disclosed in U.S. Pat. No. 4,722,097, which issued on Jan. 26, 1988 to Haendle. That patent describes an x-ray diagnostics installation with spatial frequency high-pass filtering in which the fine contrasts required in x-ray technology are intensified without the interference structures generated by the system components so as to improve the ability of the system to recognize fine details in the x-ray pictures. The system disclosed in that patent utilizes an x-ray tube in which the size of the tube focus can be varied. A video signal for an x-ray exposure produced by a given first size of the tube focus is entered into a memory and is subtracted from a previously stored video signal for an x-ray exposure recorded using a second size of the tube focus. The result of the subtraction of these two transfer functions yields a resulting transfer function in which the low frequencies are suppressed and the higher frequencies are amplified. However, the system disclosed by Haendle is complex and costly to both implement and maintain.